ePoster

Cognitive maps as expectations learned across episodes – a model of the two dentate gyrus blades

Viktor Studenyak, Jurgen Jost, Christian F. Doeller, Andrej Bicanski
COSYNE 2025(2025)
Montreal, Canada

Conference

COSYNE 2025

Montreal, Canada

Resources

Authors & Affiliations

Viktor Studenyak, Jurgen Jost, Christian F. Doeller, Andrej Bicanski

Abstract

The canonical model of the dentate gyrus (DG) of the hippocampus suggests the DG performs pattern separation, orthogonalizing similar input patterns [1, 2] aided by an approximate 5-fold expansion of the cell population relative to its entorhinal cortex inputs [3]. However, more recent experimental results challenge this standard model, suggesting the DG also supports the precise binding of objects and events to space and the integration of information across episodes [4]. Very recent studies attribute pattern separation and pattern integration to anatomically distinct parts of the DG, the suprapyramidal blade and the infrapyramidal blade respectively [5, 6]. Several models have investigated pattern separation [2], or the role of adult neurogenesis in the DG [7]. However, none have considered the role of the distinct DG blades. Here we propose the first computational model that investigates this distinction. In line with recent experimental work [6, 8] we hypothesise that the suprapyramidal blade contributes to the storage of distinct episodic memories (via pattern separation and one-shot learning). In contrast, the infrapyramidal blade integrates information across episodes (learning at a slower rate) to form generalised expectations across episodes, eventually forming a cognitive map. In the model, both new and old episodes can be compared to these learned expectations (here, expectations of positions of objects relative to oneself in a spatial layout). This comparison allows for the calculation of a prediction error, which can drive the storage of poorly predicted memories and the forgetting of well-predicted memories, thus allowing the hippocampal system to free up neuronal resources. This allows the model to iteratively build a spatial cognitive map for a familiar environment on which predictions can be generated by short-scale look-ahead.

Unique ID: cosyne-25/cognitive-maps-expectations-learned-4eaf1ce0